Recently the technologies of the liquid crystal displays have been advanced and improved quickly. Moreover, the production cost of the liquid crystal displays is continuously reduced. Therefore, the traditional cathode ray tubes (CRT) are almost completely replaced by the liquid crystal displays (LCD) in the market of the monitors. As the technologies of LCD are being improved greatly, the market of LCD TV is growing fast, and the requirements and expectations for the performance of the LCD TV become higher and higher, for example, high-resolution (e.g. 1920×1080 pixels), fast response time, no sluggish motion picture, etc.
In order to solve the problem of sluggish motion pictures in LCD TV, it is frequently necessary to double the scanning frequency from traditional 60 hertz (60 pictures per second) to 120 hertz (120 pictures per second) by inserting the pictures of the gray scale values. Although the doubled frequency can improve the fluency of the motion pictures, however the doubled frequency also reduces the driving time for each pixel, and the pixels are insufficiently changed/discharged.
For solving the above-mentioned problem, the inventor of the present invention has proposed a solution by charging/discharging with a higher voltage in the first charging/discharging period and charging/discharging with a normal ideal voltage in the second charging/discharging period in the Taiwan Patent Application No. 96115705. In this way, the pixels can still be charged/discharged to the ideal voltage, even when the charging/discharging period is reduced to one half due to the doubled frequency. The concept of this method is great. Nevertheless, as the resolution of the LCD panel becomes higher and higher up to 1920×1080 pixels (full high definition), the phenomenon of RC delay becomes even serious. There is much difference in the reachable operation voltages between the pixels near and those far from the signal terminals of the data driving chips or gate driving chips. It is explained in the following with reference to the drawings.
FIGS. 1(a)˜1(b), FIGS. 2(a)˜2(b) and FIGS. 3(a)˜3(b) are schematic diagrams showing the pixel voltages during the charging processes by using the traditional techniques. Please refer to FIG. 1(a), which is a schematic diagram showing the charging condition of the nearest pixel to the signal terminal, where the pixel voltage (Vpixel) is higher than the ideal voltage after charging, i.e. overcharging. Please refer to FIG. 1(b), which is a schematic diagram showing the charging condition of the farthest pixel from the signal terminal, where the pixel voltage (Vpixel) is the same as the ideal voltage after charging. Please refer to FIG. 2(a), which is a schematic diagram showing the charging condition of the nearest pixel to the signal terminal, where the pixel voltage (Vpixel) is the same as the ideal voltage after charging. Please refer to FIG. 2(b), which is a schematic diagram showing the charging condition of the farthest pixel from the signal terminal, where the pixel voltage (Vpixel) is lower than the ideal voltage after charging, i.e. insufficient charging. Please refer to FIG. 3(a), which is a schematic diagram showing the charging condition of the nearest pixel to the signal terminal, where the pixel voltage (Vpixel) is higher than the ideal voltage after charging, i.e. overcharging. Please refer to FIG. 3(b), which is a schematic diagram showing the charging condition of the farthest pixel from the signal terminal, where the pixel voltage (Vpixel) is lower than the ideal voltage after charging, i.e. insufficient charging.
According to FIGS. 1(a)˜1(b), FIGS. 2(a)˜2(b) and FIGS. 3(a)˜3(b), it can be known that the RC delay condition becomes serious particularly for those pixels far from the signal terminals, since the driving signals generated by the data driving chips or the gate driving chips need to pass much more other pixels in the high-resolution LCD panel. Therefore, it is hard to control the charging conditions, and the following conditions frequently occur. The pixels near the signal terminals are overcharged, as shown in FIG. 1(a), the pixels far from the signal terminals are insufficiently charged, as shown in FIG. 2(b), or even both overcharging and insufficient charging occur at the same time, as shown in FIGS. 3(a)˜3(b).
In order to solve the above-mentioned problems, the new concept and the solution method are proposed in the present invention to allow every pixel in the high-resolution LCD panel to be charged/discharged to the ideal voltage even under the operation of the doubled frequency. The present invention is described below.